CROSS_COMPILE = riscv64-unknown-elf-
CFLAGS = -nostdlib -fno-builtin -march=rv32ima -mabi=ilp32 -g -Wall

QEMU = qemu-system-riscv32
QFLAGS = -nographic -smp 1 -machine virt -bios none

GDB = gdb-multiarch
CC = ${CROSS_COMPILE}gcc
# objcopy用于将object的部分或全部内容拷贝到另一个object，从而可以实现格式的变换。
# objcopy可用用于将文件转换成S-record格式或者raw二进制格式。
OBJCOPY = ${CROSS_COMPILE}objcopy

OBJDUMP = ${CROSS_COMPILE}objdump